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O-Ring Standards 11

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jerry1423

Mechanical
Aug 19, 2005
3,428
Do O-Rings follow a particular standard that all manufactures follow, or does each manufacturer follow their own standard?
I am primarily thinking of the size dimensions here.

Jerry J.
UGV5-NX1899
 
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I believe if you see a dash number (-001,-002, etc.) that will correspond to a certain standard size.
 
It is good that you only asked about size and not materials.
The only restriction are on the base resin and hardness.
Other than that all bets are off.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
 
Just Google up the Parker O-Ring Handbook..

Regards

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand
 
The Parker handbook covers the NAS sized o-rings but there are quite a few metric standards out there as well. There are both ISO and JIS sizing standards for o-rings.
 
As previously stated there are plenty of O-ring standards out there, most common ones being:

ISO 3601-1
AS 568
JIS B 2401
SMS 1586
BS 1806

An O-ring groove should be designed in accordance with the sizes stated in those standards. That being said, it is possible to order custom made O-rings (both material composition and size) from a lot of the O-ring manufacturers. You will have to pay for the manufacturing setup cost, but it is fully doable.
 
Thank you so much for all the replies.
I do primarily use the Parker handbook, and I find it invaluable, but I was uncertain if other manufacturers follow what they do.
I am in process of writing company standards and new numbering system, and I want to make sure I have everything covered.

Jerry J.
UGV5-NX1899
 
Aerospace Recommended Practice "ARP568" defines Uniform dash numbering for O-ring. In 1971 SAE replaced this name as AS568 (Aerospace Standard).
There are 2 classes of tolerances for Internal diameters. Most common c/s - 1.78, 2.62, 3.53, 5.33, 6.99 and some additional ARP 900.

Each 3 digit dash no. has a standard ID and C/s. 1st digit says c/s ("0 - 1.78"; "1 - 2.62"; "2 - 3.53";...)and remaining 2 digits is random numbering for which std. needs to be referred to identify the ID of O-ring.

ISO 3601 follows the same SAE Aerospace Size Standard dash nos. and also mentions the 2 different class of tolerances Class A and Class B.
This standard is commonly manufactured by all the O-ring manufacturers. It is best to use this standard as per my experience.
ISO 3601 also defines tolerance bands for other sizes too.

Of course many other standards as mentioned by others can be followed.

O-rings are very simple profile seals and do not have any limitation for any sizes. Hence can be manufactured for other c/s's and ID's based on the hardware packaging available in application.

Hope this helps

Thanks.
 
Nobody is voluntarily making custom section o-rings. They almost always conform to one standard or another. The key here is recognize the diverse standards that do exist and how to compare them to correctly identify o-rings dimensions.
 
McMaster Carr is really excellent for this. Just search "o-ring" and you'll have everything you need. FWIW - the McMaster price is often cheaper than a distributor in my experience (mostly with standard EPDM o-rings) - even at volumes of 500 units +

I also love this calculator:
 
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